There's been a lot of debate in the tech world over the past few months about whether the ARM-based versions of Windows 8 should be "pure" tablets, providing only the Metro-style Start screen experience, or full-fledged Windows machines, offering the classic Windows desktop as well. It's a good question, and one that I ponder regularly. But some have asked whether there isn't a third option.

This so-called third option is often described, erroneously, I think, as "the best of both worlds." And the theory goes something like this:

While in slate form, detached from any dock or keyboard, an ARM-based Windows 8 tablet would simply offer the Start screen and access to Metro-style apps.

But while docked or attached to a keyboard, the same ARM-based Windows 8 tablet would also offer the full desktop experience, and access to legacy Windows applications.

But this raises its own questions. Most obviously: Does this configuration even make sense?

No, it does not.

Let's say you use Microsoft Word 2010 to edit word processing documents. Even while in a pure tablet mode, you may want to read these documents and do light editing. But if Windows "hid" the desktop from you, along with its apps, this would be impossible. (Using the same app. Obviously, you could use some other Metro-style app instead. But how weird would that be?)

Windows is not about limiting the user in this way. There are no "modes." If anything, there are too many ways to accomplish many actions, thanks to the Windows' need to serve so many different audience types.

Ultimately, the decision on ARM-based Windows 8 tablets comes back to the original two choices:

- They will provide the full desktop experience, which will be a bit jarring and odd for users of pure tablets, and not fully compatible with legacy Windows applications, which will likewise be odd.

Or...

- They will not provide access to the legacy Windows desktop, which will provide a more "pure" tablet experience, one that is in many ways similar to that on the iPad.

Pedantically, you could argue that the latter option is "limiting." But I don't see that at all. It's worse to provide access to a desktop environment that would suggest to people that all those previous Windows applications will work just fine, when in fact they will not. I think the big break here needs to happen on the ARM side, and this transition was previously mirrored when certain legacy features were removed from 64-bit bit versions of Windows XP, Vista, and 7. A processor architecture change is the ideal, obvious, and logical time and place to make this break.